firefox2koreader/firefoxplugin/background.js

/* https://stackoverflow.com/a/71604665 */
const imageUrlToBase64 = async url => {
  const response = await fetch(url);
  const blob = await response.blob();
  return new Promise((onSuccess, onError) => {
    try {
      const reader = new FileReader() ;
      reader.onload = function(){ onSuccess(this.result) } ;
      reader.readAsDataURL(blob) ;
    } catch(e) {
      onError(e);
    }
  });
};


/* https://stackoverflow.com/a/48032528 */
async function replaceAsync(str, regex, asyncFn) {
    const promises = [];
    str.replace(regex, (match, ...args) => {
        const promise = asyncFn(match, ...args);
        promises.push(promise);
    });
    const data = await Promise.all(promises);
    return str.replace(regex, () => data.shift());
}

browser.browserAction.onClicked.addListener(async (tab) => {
    try {
        const result = await browser.tabs.executeScript(tab.id, {
            file: "/Readability.js"
        });
        const articleHtml = result[0]["body"];
        const pageUrl = result[0]["url"];
        const baseUrl = result[0]["baseurl"];
        //console.log("Obtained result: ", baseUrl, articleHtml);

        // Replace all URLs with data-urls
        const srcRegexp = /src="(https?:\/\/.+?)"/g;

        const inlinedImageHtml = await replaceAsync(articleHtml, srcRegexp, async function(match, src) {
            let absoluteUrl;
            if (src.startsWith('http://') || src.startsWith('https://')) {
                absoluteUrl = src;
            } else {
                absoluteUrl = baseUrl + "/" + src;
            }

            const dataUrl = await imageUrlToBase64(absoluteUrl);

            return "src=\"" + dataUrl + "\"";
        });
        console.log("All matching done", inlinedImageHtml)



        const url = (await browser.storage.local.get("koreaderurl")).koreaderurl;
        console.log("posting to " + url);
        try {
            await fetch(url, {
                method: 'POST',
                body: inlinedImageHtml
            });
        } catch(error) {
            throw 'KOReader server unreachable, check connection and URL in settings';
        }
    } catch(err) {
        browser.notifications.create({
            'type': 'basic',
            'message': 'Could not post article to KOReader: ' + err,
            'title': 'Firefox2KOReader'
        });
    }

})

//browser.tabs.onCreated.addListener(() => {
//    browser.browserAction.disable()
//})
//browser.tabs.onUpdated.addListener((tabId, changeInfo, tab) => {
//    console.log("Tab updated!", tab)
//    if (tab.isInReaderMode) {
//        browser.browserAction.enable()
//    } else {
//        browser.browserAction.disable()
//    }
//
//})